Yeah, I used to do that as well, until I realised that it wasn't doing me any favours at all and there was no benefit for anyone by me playing myself down. It was about the time I realised when I just started being more open, honest and kind, and to hell with anyone else's preconceived notions! :P
It's not easy, but it's not hard either. It just takes a bit of dedication and wanting to be yourself more than to have other people like a fake you. If you like being fake then there's no reason to alter, but I don't think you do like being fake. :P It also helps to build self worth, explore who you really are and what matters, and find friends who are worthy and decent.
It's so worth it though, the time will pass anyways and at the end of it you'll have so much more respect for who you are and people who like you for you are such better friends.
You'll also have a real direction to guide yourself instead of the fickle winds of social acceptance and being liked.
So, ready to be yourself? :P